In the game of tennis, wherein the spin of the ball becomes important to the participant in being able to learn how to impart spin to the ball and therefore exercise some control in delivery of the ball, or alternately, to be able to determine the spin or rotation of the ball when the ball is to be returned, hit or otherwise acted upon, it becomes important to be able to visually perceive the spin or rotation of the tennis ball during flight. For example, in playing tennis, especially in the neophyte stages, the ball delivery becomes important with regard to the type of spin that may be wished to be imparted to the ball so that the opponent will not be likely to return the ball, because of the change in trajectory of the ball in flight caused by imparted spin to the ball, as by contacting the ball in a specific manner with a tennis racket.
In also receiving the ball, a tennis player, in order to return the ball effectively, must ascertain the type of spin which has been imparted to the ball so as to be able to compensate in the return stroke for the spin or rotation of the ball in flight during trajectory. Additionally, visual observation of the spin of the ball will also allow the receiver of the ball to ascertain with some certitude the likely point of impact of the ball, to which a spin has been imparted, and the likely bounce trajectory that the ball will take thereby enabling the player to effectively position himself for return of the ball.
Heretofore, tennis balls, have had no visual means to aid in training in either delivering or returning the ball by determining the spin or rotation of the ball. Traditionally the tennis balls have been an all white or off-white color, or in recent years, of different solid colors making it difficult to know and to effectively perceive the spin that has been imparted to the ball in order to more effectively deliver or return the tennis ball.
With the herein disclosed invention, tennis ball spin is easily ascertained and is perceptible by the utilization of at least surface means on the exterior of the ball which, in conjunction with the remainder of the surface of the ball, produces a dynamic pattern which is easily perceived while the ball is in flight.